Laser tweezers manipulate objects just 50 nanometers wide

Technique could allow scientists to move proteins, viruses and nanomaterials

BEAD CAPTURE A 50-nanometer-wide plastic bead (yellow circle, center) is trapped by light in this illustration. Laser light gets focused by a bow tie–shaped hole etched into a thin gold film at the tip of an optical fiber.

A new set of laser tweezers offers scientists unprecedented control over objects just tens of billionths of a meter in size. The device could allow biologists to probe individual viruses and proteins without risk of frying them.

“It’s a very clever method,” says Phil Jones, an optics physicist at University College London. “You can trap much smaller objects with much less laser power.”

Since the 1980s, scientists have studied molecules, bacteria and other minuscule objects under the microscope by trapping them with laser light. Lenses focus the light toward the sample, and subtle forces exerted by the light nudge the object toward the center of the beam.

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